Locking Bone Screws and Methods of Use Thereof

ABSTRACT

The invention encompasses a bone screw for use in the human body including a shaft having a threaded region along at least a portion of its length and a screw head including a locking mechanism to secure the screw, for example to a bone plate. In certain embodiments, the thread has an outer diameter dimensioned to pass through the screw hole in the implant. The screw head is configured to cooperatively engage at least a portion of the screw hole of the implant so as to prevent the screw from coming out of the implant and avoided soft tissue damage and other complications associated with unintended screw removal.

FIELD OF THE INVENTION

The invention encompasses a bone screw for use in the human bodyincluding a shaft having a threaded region along at least a portion ofits length and a screw head including a locking mechanism to secure thescrew, for example to a bone plate. In certain embodiments, the threadhas an outer diameter dimensioned to pass through the screw hole in theimplant. The screw head is configured to cooperatively engage at least aportion of the screw hole of the implant so as to prevent the screw fromcoming out of the implant and avoided soft tissue damage and othercomplications associated with unintended screw removal.

BACKGROUND OF THE INVENTION

Many surgical procedures require securing an implant to bone, forexample, to vertebrae along the spine. Orthopedic fixation devices arefrequently coupled to bone by the use of fasteners such as screws,threaded bolts, or pins. For example, bone plates can be secured to bonewith bone screws, inserted through plate holes.

Securing the screws to the plate provides a fixed angle relationshipbetween the plate and screw and reduces the incidence of loosening.Current techniques involve a locking screw that has threading on anouter surface of its head that matches with corresponding threading onthe surface of a plate hole to lock the screw to the plate. Bone plateshaving threaded holes for accommodating locking screws are used withsuch screws.

For example, as a screw is being inserted into bone through the bushingand plate hole, a threaded tapered head of the screw engages a threadedinternal surface of the bushing to expand the bushing against the wallof the plate hole, thereby friction locking the screw at the desiredangular orientation with respect to the plate.

These multi-component traditional plate assemblies can be cumbersome andtedious to manipulate during surgery to achieve the most desirable anglefor directing the bone screw into the patient.

The inventors have developed bone screws with locking mechanisms toprovide retention of the screws with a bone plate and/or with the boneto prevent movement or unintended removal of the screw from the plate.

SUMMARY OF THE INVENTION

The invention generally encompasses bone screws including a screw headand a proximal shaft adapted to be secured to a bone, wherein the screwhead comprises a plurality of flexible elements for engaging the screwhead portion of the bone screw in a locking arrangement with a boneplate such that the flexible elements decrease the outer diameter of thehead portion during insertion into a bone plate and expand afterinsertion is completed thereby locking the screw to the bone plate.

In another embodiment, the invention encompasses a bone screw comprisinga screw head and a proximal shaft adapted to be secured to a bonewherein the head comprises a locking cap comprising:

(i) a plurality of fingers projecting upwardly from the shaft forming aninner diameter in the head portion; and

(ii) a rotatable locking cap located in said inner diameter of the headportion such that rotation of the locking cap engages the cap with thefingers causing a positive locking feature.

In another embodiment, the invention encompasses a locking bone screwcomprising a screw head and a proximal shaft adapted to be secured to abone wherein the head portion comprises:

(i) an inner bore;

(ii) a plurality of finger elements projecting upwardly from the shaftforming the inner bore with an inner diameter in the head portion; and

(iii) a rotatable locking cap located in said inner diameter of the headportion such that rotation of the locking cap engages the cap with thefingers causing a positive locking feature.

In another embodiment, the invention encompasses a locking screwcomprising a screw head and a proximal shaft, wherein the screw headcomprises an inner bore and collapsible finger elements and aninsertable locking plug located in the inner bore of the screw head,wherein the locking plug can be depressed and rotated to engage apositive locking feature.

In another embodiment, the bone screw according to the present inventionincludes an elongate shaft having a lower threaded body for fixation toa bone. The shaft further has an upper locking structure connected tothe threaded body by a neck. The locking structure has an upper end thatcan be compressed in an inner diameter surrounded by a plurality offinger elements to engage a positive locking feature.

In another embodiment, the invention encompasses a bone screw lockcomprising:

(i) a screw head;

(ii) a proximal bone screw hole/plate; and

(iii) a locking insert, wherein the screw head is spherical in diameterand is split with a plurality of finger elements, which are capable ofdeflecting in and out, the bone screw hole is spherical, which matchesthe screw head such that the screw can be placed into a bone plate at anangle and or provide screw angulation; and the locking insert comprisesa shaft that has a plurality of arms that mate with the finger elementsthat divide the screw head.

In another embodiment, the invention encompasses a method of using alocking bone screw of the invention to secure a bone plate or rod to thescrew and a bone.

BRIEF DESCRIPTION OF THE FIGURES

A more complete understanding of the present invention may be obtainedby reference to the accompanying drawings, when considered inconjunction with the subsequent detailed description. The embodimentsillustrated in the drawings are intended only to exemplify the inventionand should not be construed as limiting the invention to the illustratedembodiments, in which:

FIG. 1 illustrates a non-limiting, exemplary view of a bone screw of theinvention including a flexible locking screw head.

FIGS. 2A and 2B illustrate perspective views of non-limiting, exemplarybone screws of the invention.

FIG. 3A illustrates a top plan view of non-limiting, exemplary flexiblebone screw heads including locking tabs. FIG. 3B illustrates a bottomplan view of non-limiting, exemplary flexible bone screw heads includinglocking tabs. FIG. 3C illustrates a side perspective view ofnon-limiting, exemplary bone screws.

FIG. 4A illustrates a top plan view of a non-limiting, exemplaryflexible bone screw head including a square socket driver. FIG. 4Billustrates a bottom plan view of a non-limiting, exemplary bone screw.FIG. 4C illustrates a side plan view of a bottom tip of a non-limiting,exemplary bone screw. FIG. 4D illustrates side perspective views ofnon-limiting, exemplary flexible bone screws.

FIG. 5A illustrates cross-sectional views of locking bone screwincluding an internal locking cap that includes a gap in the unlockedposition and an interference in the locked position. FIG. 5B illustratesa top plan view of non-limiting, exemplary bone screw heads including anelliptical locking cap that can be engaged by rotating the locking capin a plurality of fingers protruding upwardly from the shaft of thescrew. FIG. 5C illustrates a top plan view of non-limiting, exemplarybone screw heads including an polygonal locking cap that can be engagesby rotating the locking cap in a plurality of fingers protrudingupwardly from the shaft of the screw. FIG. 5D illustrates an exemplary,non-limiting bone plate that can be utilized with the locking bonescrews of the invention.

FIGS. 6A and 6B illustrate non-limiting, illustrative embodiments oflocking screws comprising a head portion including an inner bore andcollapsible finger elements protruding upwardly from the shaft of thescrew and a locking plug located in the inner bore of the screw head.

FIG. 7 illustrates a non-limiting, exemplary locking insert, which isspherical in diameter and includes a plurality of fingers, which allowthe screw head to deflect in and out to engage a positive lockingfeature.

FIG. 8 illustrates a non-limiting, exemplary embodiment of a screw headand a proximal shaft, wherein the screw head comprises four (4) armsthat mate with the fingers of the locking insert.

FIG. 9 illustrates a non-limiting, exemplary bone screw locking headcomprising (i) a screw head and (ii) a locking insert.

DETAILED DESCRIPTION OF THE INVENTION

Detailed embodiments of the invention are disclosed herein; however, itis to be understood that the disclosed embodiments are merely exemplaryof the invention, which may be embodied in various forms. Therefore,specific structural and functional details disclosed herein are not tobe interpreted as limiting, but merely as a basis for the claims and asa representative basis for teaching one skilled in the art to variouslyemploy the present invention in virtually any appropriately detailedstructure.

Accordingly, in one embodiment the invention encompasses a locking bonescrew comprising a screw head and a proximal shaft adapted to be securedto a bone, wherein the head portion comprises one or more flexibleelement(s) for engaging the head portion of the bone screw in a lockingarrangement with a bone plate such that the flexible elements decreasethe outer diameter of the head portion during insertion into a boneplate and allow the head portion to lock to the bone plate.

In certain embodiments, the head portion is substantially spherical.

In certain embodiments, the shaft portion is at least partiallythreaded.

In certain embodiments, the flexible elements of the head portioncomprise tabs for engaging (i.e., locking) with a bone plate.

In certain embodiments, the head portion comprises a square socketdriver. In certain embodiments, the screw head comprises a hexagonalsocket driver.

In certain embodiments, the flexible elements are configured to lock thebone screw to a fixation rod.

In certain embodiments, the flexible elements further includeserrations.

In certain embodiments, the screw head further comprises one or morelocking clips. In certain embodiments, the locking clips are configuredto engage and lock a bone plate with the screw.

In another embodiment, the invention encompasses a locking bone screwcomprising a screw head portion and a proximal shaft adapted to besecured to a bone wherein the head portion comprises (i) an inner bore;(ii) a plurality of finger elements projecting upwardly from the shaftforming the inner bore with an inner diameter in the head portion; and(iii) a rotatable locking cap located in said inner diameter of the headportion such that rotation of the locking cap engages the cap with thefinger elements causing a positive locking feature.

In certain embodiments, the shaft is at least partially threaded.

In certain embodiments, a gap exists between the locking cap and fingerswhen the locking cap is in the unlocked position. In certainembodiments, when the locking cap is in the locked position aninterference is caused between the locking cap and finger elements.

In certain embodiments, the locking cap is substantially elliptical.

In certain embodiments, the locking cap is substantially polygonal.

In certain embodiments, the screw head comprises a hexagonal socketdriver. In certain embodiments, the screw head comprises a square socketdriver.

In certain embodiments, the finger elements are configured to secure thebone screw to a bone plate.

In certain embodiments, the finger elements further include serrations.

In another embodiment, the invention encompasses a locking screwcomprising a screw head and a proximal shaft, wherein the screw headcomprises an inner bore and collapsible finger elements and a lockingplug located in the inner bore of the screw head.

In certain embodiments, the shaft is at least partially threaded.

In certain embodiments, the screw head further comprises smallerdiameter screw hole located in the inner bore.

In certain embodiments, the locking plug engages with the screw headportion by inserting the locking plug into smaller diameter screw holelocated in the inner bore.

In certain embodiments, the locking plug engages with the screw headportion by pushing the locking plug into the screw head and rotating.

In certain embodiments, the locking plug engages with the screw headportion by rotating the locking plug.

In certain embodiments, the diameter of the inner bore is increased whenthe screw is in the locked position.

In certain embodiments, the diameter of the inner bore of the screw headis substantially elliptical.

In certain embodiments, the diameter of the inner bore of the screw headis substantially spherical.

In certain embodiments, the head portion comprises a hexagonal socketdriver. In certain embodiments, the screw head comprises a square socketdriver.

In certain embodiments, the finger elements are configured to lock thebone screw to a bone plate.

In certain embodiments, the fingers further include serrations.

In another embodiment, the invention encompasses a locking bone screwcomprising (i) a screw head; (ii) a proximal bone screw hole/plate; and(iii) a locking insert, wherein the screw head is spherical in diameterand is split with a plurality of finger elements, which are capable ofdeflecting in and out, the bone screw hole in plate is spherical, whichmatches the screw head such that the screw can be placed into a boneplate at an angle and or provide screw angulation; and the lockinginsert comprises a shaft that has a plurality of arms that mate with thefinger elements that divide the screw head.

In certain embodiments, the screw head is able to flex inward enough toallow the screw to pass through an interference point in the bone screwhole in the plate.

In certain embodiments, the screw head comprises a hex incorporated intoit for driving the screw. In certain embodiments, proximal the hex is agroove which creates a cavity that the locking insert communicates,which retains the locking insert in the screw head.

In certain embodiments, the locking insert is a separate component thatis assembled into the screw head to provide the screw lock.

In certain embodiments, the core diameter of the locking insertcomprises a stop to the screw head and prevents any deflection.

The locking screws of the invention may include polyaxial screws,expandable screws, which when inserted or screwed into the bone andexpand by way of some type of expansion mechanism, conventional screws,and the like. In certain embodiments, the screws can be coated with anynumber of suitable osteoinductive or osteoconductive materials toenhance fixation in the bone. In another embodiment, the screws coatingenhance bony in-growth or to further anchor the screw to the bone.

The locking screws may be made from a host of materials. For example,the locking screws may be formed from natural/biological materials, suchas allograft, xenograft, and cortical bone. The locking screws may alsobe formed from synthetic bio-resorbable materials, such aspolyanhydride, polyactide, polyglycolide, polyorthoester,polyphosphazene, calcium phosphate, hydroxyapatite, bioactive glass,tyrosine-derived polycarbonate, and mixtures thereof.

In other embodiments, the locking screw of the invention is formed ofany suitable biocompatible material(s) of sufficient strength to allowthe screw to be implanted into a bone. Exemplary biocompatible materialsinclude (1) metals (for example, titanium or titanium alloys, alloyswith cobalt and chromium (cobalt-chrome), stainless steel); (2) plastics(for example, ultra-high molecular weight polyethylene (UHMWPE),polymethylmethacrylate (PMMA), polytetrafluoroethylene (PTFE),polyetheretherketone (PEEK), nylon, polypropylene, and/orPMMA/polyhydroxy-ethylmethacrylate (PHEMA)); (3) ceramics (for example,alumina, beryllia, calcium phosphate, and/or zirconia, among others);(4) composites; (5) bio-resorbable (bioabsorbable) materials or polymers(for example, polymers of alpha-hydroxy carboxylic acids (e.g.,polylactic acid (such as PLLA, PDLLA, and/or PDLA), polyglycolic acid,lactide/glycolide copolymers), polydioxanones, polycaprolactones,polytrimethylene carbonate, polyethylene oxide,poly-beta-hydroxybutyrate, poly-.beta.-hydroxypropionate,poly-delta-valerolactone, other bio-resorbable polyesters, and/ornatural polymers (such as collagen or other polypeptides,polysaccharides (e.g., starch, cellulose, and/or chitosan), anycopolymers thereof); (6) bone tissue (e.g., bone powder and/or bonefragments); and/or the like. The materials may be partially orcompletely bio-resorbable, as desired or appropriate. In otherembodiments, the materials may be partially or completely implantable,as desired or appropriate.

In addition, the locking screws may include growth factors for boneingrowth and bony attachment, or for soft tissue ingrowth. Non-limitingexamples of growth factors include insulin-like growth factor 1, basicfibroblast growth factor, transforming growth factor beta-1,platelet-derived growth factor, bone-derived growth factors, arginine,bone morphogenetic protein, LIM mineralization protein, and combinationsthereof.

Referring particularly to FIGS. 1-9 a bone screw is shown which isfabricated of a well known biocompatible material, for example, such asstainless steel, titanium or titanium allow and has a locking screw headand a cylindrical shaft with a tapered a tip remote from the screw head.

With reference to FIG. 1, two bone screws 100 a and 100 b are shownaccording to one embodiment of the invention. In this embodiment, thebone screws 100 comprise, concentric to the longitudinal axis of thescrew, a screw shaft 101 and a screw head 120, wherein the screw head120 and optionally the entire screw is made of flexible elements thatallow the screw head 120 to temporarily decrease its outer diameterduring insertion into, for example, a bone plate. The decrease willallow the screw to pass into the plate and past an otherwise retaininginterfering retainment ring.

In certain embodiments, the screws 100 a and 100 b include a squaredriver 130 instead of a hexagonal driver to reduce the possibility ofthe driving geometry stripping.

The bone screws 100 a and 100 b in certain embodiments also includestabs 140 in the screw head to allow a more secure or locking fit with abone plate. For example in certain embodiments, the tabs 140 lock thescrew head into fixed frictional contact so as to fix the screw in aone-step lock. In certain embodiments, because of the flexible nature ofthe screws 100 a and 100 b, the head 120 and shaft 101 cooperate in sucha manner that the head 120 and shaft 101 can be secured at any of aplurality of angles, articulations or rotational alignments relative toone another and within a selected range of angles both from side to sideand from front to rear, to enable flexible or articulated engagementuntil the screw head is locked or fixed with a bone plate near an end ofan implantation procedure.

With reference to FIGS. 2 a and 2 b, the shaft 201 is elongate, with theshaft body having a helically wound bone engaging thread 220 extendingfrom near a neck 226 located adjacent to the screw head to near a tip228 of the body and projecting radially outward therefrom.

During use, rotation of the body utilizes the thread 220 for grippingand advancement in the bone and is implanted, for example, into avertebra leading with the tip 228 and driven down into the vertebra withan installation or driving tool, so as to be implanted in the vertebranear the neck 226.

The neck 226 extends axially outward and upward from the shaft body 201to a flexible locking screw head. The neck 226 generally has a reducedradius as compared to the screw head 230.

The screwhead includes flexible tabs 240 that allow locking with a boneplate.

FIGS. 3A and 3B illustrate top and bottom plan views of the screw. Thescrew head 330 had flexible tabs 340 protruding from the screw head 330to pass through a bone plate and thereby lock with the bone plate.

FIG. 3C illustrates a threaded bone screw including a shaft 301 withthreads 320 and a screw head 330 with one or more flexible elements 340protruding from the screw head and a tapered tip 328 distal from thescrew head.

FIGS. 4A and 4B illustrate top and bottom plan views of the screw. Thescrew head 430 is substantially spherical and flexible in nature toallow the screw head to pass through a bone plate and thereby lock withthe bone plate. In an illustrative embodiment, the screw head includes asquare driver.

FIG. 4C illustrates an illustrative tapered tip portion 428 at thedistal end of the shaft opposite the screw head to allow insertion intoa bone or callous tissue.

FIG. 4D illustrates a threaded bone screw including a shaft 401 withthreads 420 and a screw head 430 with one or more flexible elements 440protruding from the screw head and a tapered tip 428 distal from thescrew head.

Another embodiment illustrated in FIG. 5A encompasses a bone screwincluding a distal head portion 550 and a proximal shaft portion (notillustrated) adapted to be secured to a bone and, for example, a boneplate, wherein the screw head 550 comprises (i) a plurality of fingers555 projecting upwardly from the shaft forming an inner diameter 558 inthe head portion and (ii) a rotatable locking cap 552 located in saidinner diameter of the head portion such that rotation of the locking capengages the cap with the fingers causing a positive locking feature(i.e., interference).

The screw head 550 with an inner bore 558 and collapsible fingerselements 555 is optionally pre-assembled with a locking cap 552 capableof inserting into a smaller diameter screw hole.

The inner bore of the screw head allows deflection of the fingers whilethe screw is inserted into the plate hole. Initially, the locking cap isin position where there is a gap 560 between the cap 552 and the fingers555. When the locking cap is turned, it adds interference 570 to thescrew head, preventing collapse of screw head (fingers) and/or addinginterference 570 to increase screw head's spherical diameter thuslocking it, for example, with a bone plate.

The invention encompasses various different locking caps. FIG. 5Billustrates an elliptical locking cap, and FIG. 5C illustrates apolygonal locking cap.

Initially during insertion of the screw into bone, major and minordiameters of the screw (inner diameter) are aligned with major and minordiameter of the locking cap. There are just enough gaps betweenelliptical shaped cap and elliptical screw head (inner hole), whichallows finger of the screw head to collapse during the screw to plateinsertion. Once the screw is seated in the plate, the elliptical headcan be turned, for example, about 90° to remove the gap and/or addadditional interference to two fingers of the screw head. At this point,major and minor diameter between locking cap and screw is shifted,producing a positive locking feature as illustrated in FIGS. 5B and 5C.

In another illustrative, non-limiting embodiment a polygonal shapedlocking cap has side rotates at an angle to add interference to all ofthe fingers of the screw head. The bumps 580 on the side prevent overturning as illustrated in FIGS. 5B and 5C. (A circular head is alsoconsidered to be a polygon of infinite number of sides).

In various embodiments, the screw applications can also implemented onthe thin plate, for example illustrated in FIG. 5D, adding a top andbottom surface bumpers to produce smaller screw entrance.

Advantages of the current locking screw include, but are not limited to,the final product (screw) is one piece design, the screw locking can bedone in a single step, screw locking is visible, audible and/or tactile,the invention prevents the screw from going thru the plate, and thescrew design can be implemented to the thinner plate design with bumpadded.

In another embodiment, as illustrated in FIG. 6A, the inventionencompasses a screw head 600 with an inner bore 610 and collapsiblefinger elements 620 is pre-assembled with a Hex locking plug 630, whichis capable of fitting into the smaller diameter screw hole 640.

The inner bore 610 of the screw head allows deflection of the fingerswhile the screw is inserted into the plate hole as illustrated in FIG.6B. Initially, the locking plug is in position where there is a gapbetween the plug and the finger elements. The male portion 650 of thelocking plug 630 also drives the screw body into the bone. When thescrew is fully seated and the locking plug is pushed down (locked) witha low impact push button hex driver, it adds interference to the screwhead, preventing collapse of screw head (fingers) and/or increases screwhead spherical diameter.

Another embodiment encompasses a locking screw including three pieces: ascrew head 800, a plate bone/hole screw 820 illustrated in FIG. 8, and alocking insert illustrated in FIG. 7.

In an illustrative embodiment, the screw head 800 is spherical indiameter and is split with about four (4) grooves 810, which allow thescrew head to deflect in and out. The grooves 810 are able to flexinward enough to allow the screw to pass through an interference pointin the bone screw hole in a bone plate. The screw head also optionallyhas a hex incorporated into it for driving the screw.

At the bottom of the hex, a groove is placed which creates the cavity830 that clips 710 of the locking insert 700 snap into, which retainsthe locking insert in the screw head.

The hole in a bone plate (not illustrated) is spherical, which matchesthe screw head so that the screw can be placed into the plate at anangle and or provide screw angulation. Closer to the top surface of theplate at the upper portion of the bone screw sphere, a slightlyundersized through hole provides the interference to keep the screwretained once the locking insert is engaged.

Referring to FIG. 9, the locking insert 700 is a separate component thatcan be inserted into the screw head to provide the screw lock. Thelocking insert includes a shaft 720 that comprises a plurality of armsthat mate with the. The locking insert 700 has (4) arms 710 extendingfrom the shaft 720 that mate with the finger elements 810 that split thescrew head and provide the screw lock. The (4) arms 710 communicate in alocking manner with the slots 810 that split the screw head 800. Alongwith the slots 810, the core diameter provides a stop to the screw headand prevents any deflection. The tip of the insert 820 is tapered and isalso split (4) ways to allow the insert to snap into the screw head andengage the groove in the bottom of the hex.

The main surgical advantage of the mechanism is that it provides anaudible, tactile, and visual indication that the screw is locked,without adding thickness to the plate itself. This lock fits into thescrew head and is low profile. Since it is so easy to install, thesecond step required to insert the lock is negligible.

This lock can also be removed with the proper instrumentation and willwork when the screws are angulated in the plate. The tapered tip on theLocking Insert makes it self-starting and easy to engage.

Since the lock is a separate component, it makes the plates and bonescrews easier to machine because usually these locks historicallyrequire tedious assembly and or small highly tolerance parts to makethem work.

In will be appreciated that different types of screw assemblies can beincorporated with the lock screws of the invention, for example,polyaxial screws. In addition, the screws illustrated herein includethreads. It is foreseen that other thread types, such as V-threads,square threads, other inverted thread types or other thread like ornon-thread like guide and advancement structures, such as flange form,helically wound advancement structures may be utilized according to theinvention. Other preferred thread-types also include square threads withwide strong teeth and greater surface contact as well as modifiedinverted buttress threads, for example buttress threads wherein theangular relationship between the trailing and leading surfaces aremodified somewhat, or wherein the size, shape or orientation of theconnecting wall between the leading and trailing surfaces is modifiedsomewhat.

Methods of Use

The invention encompasses a locking screw for use in implantation ofscrews in a bone cavity of a subject requiring stabilization orimmobilization of one or more bones (e.g., vertebrae).

Specifically, the invention encompasses a bone screw for use in thehuman body including a shaft with a thread along at least a portion ofits length and a locking mechanism to secure the screw, for example to abone plate or rod.

In certain embodiments, the thread has an outer diameter dimensioned topass through the screw hole in the implant. The trailing end of thescrew (e.g., the screw head) is configured to cooperatively engage atleast a portion of the screw hole in the plate or rod of the implant soas to prevent the screw from linear motion along the mid-longitudinalaxis of the shaft in a direction opposite to the direction of insertionwhen the screw is secured to the screw hole to attach the implant to abone portion of the human body.

The locking screw of the invention can be implanted and used to fastenvarious different types of bones (e.g., hip, femur, vertebra).

In certain embodiments, the invention encompasses a locking bone screwuseful for fixing or pre-mounting a fastening device on the bone screw,which can be implanted by minimal invasive surgery where appropriate.

In certain embodiments, included on the locking screw is a fasteningdevice, where the fastening device displays an extension that can engagethe bone screw. In other embodiments, the locking screw and thefastening device comprise a single body.

In another embodiment, the invention encompasses methods for treating ansubject requiring bone containment comprising:

a. creating a cavity in a vertebral body;

b. inserting into the cavity a locking screw; and

c. attaching a bone plate or rod; and

d. locking the screw to the bone plate.

Kits

The invention also contemplates kits including various locking screws ofthe invention as wells as the tools needed for surgery, for example,flexible segment portions or rigid rods for use in spinal surgery. Thelocking screws may be manufactured in varying widths and lengths toaccommodate the type of surgery and needs of the surgeon.

The kits of the invention are intended to broaden a surgeon's optionsonce in surgery to provide a patient with the most optimal stabilizationsystem. By containing the most common locking screws, instrument needsand options for assembling actual spine stabilization, the revisions arecompleted faster and with fewer sets from central supply. Overall, thereis less of a labor burden on hospital staff and procedure time isreduced by having all required instruments in one convenient kit.

It is to be understood that while certain forms of the present inventionhave been illustrated and described herein, it is not to be limited tothe specific forms or arrangement of parts described and shown.

In the specification, there have been disclosed typical preferredembodiments of the invention and, although specific terms are employed,they are used in a generic and descriptive sense only and not forpurposes of limitation. Obviously many modifications and variations ofthe invention are possible in light of the above teachings. It istherefore to be understood that the invention may be practiced otherwisethan as specifically described.

Unless defined otherwise, all technical and scientific terms and anyacronyms used herein have the same meanings as commonly understood byone of ordinary skill in the art in the field of this invention.Although any compositions, methods, kits, and means for communicatinginformation similar or equivalent to those described herein can be usedto practice this invention, the preferred compositions, methods, kits,and means for communicating information are described herein.

All references cited above are incorporated herein by reference to theextent allowed by law. The discussion of those references is intendedmerely to summarize the assertions made by their authors. No admissionis made that any reference (or a portion of any reference) is relevantprior art. Applicants reserve the right to challenge the accuracy andpertinence of any cited reference.

1. A locking bone screw comprising a screw head and a proximal shaftadapted to be secured to a bone, wherein the head portion comprises oneor more flexible element(s) for engaging the head portion of the bonescrew in a locking arrangement with a bone plate such that the flexibleelements decrease the outer diameter of the head portion duringinsertion into a bone plate and allow the head portion to lock to thebone plate.
 2. The bone screw of claim 1, wherein the head portion issubstantially spherical.
 3. The bone screw of claim 1, wherein the shaftportion is at least partially threaded.
 4. The bone screw of claim 1,wherein the flexible elements of the head portion comprise tabs forengaging a bone plate.
 5. The bone screw of claim 1, wherein the headportion comprises a square socket driver.
 6. The bone screw of claim 1,wherein the flexible elements are configured to lock the bone screw to afixation rod.
 7. The bone screw of claim 1, wherein the flexibleelements further include serrations.
 8. The bone screw of claim 1further comprising one or more locking clips.
 9. The bone screw of claim8, wherein the locking clips are configured to engage and lock a boneplate with the screw.
 10. A locking bone screw comprising a screw headportion and a proximal shaft adapted to be secured to a bone wherein thehead portion comprises (i) an inner bore; (ii) a plurality of fingerelements projecting upwardly from the shaft forming the inner bore withan inner diameter in the head portion; and (iii) a rotatable locking caplocated in said inner diameter of the head portion such that rotation ofthe locking cap engages the cap with the fingers causing a positivelocking feature.
 11. The bone screw of claim 10, wherein the shaft is atleast partially threaded.
 12. The bone screw of claim 10, wherein a gapexists between the locking cap and fingers when the locking cap is inthe unlocked position.
 13. The bone screw of claim 10, wherein thelocking cap is substantially elliptical.
 14. The bone screw of claim 10,wherein the screwhead comprises a hexagonal socket driver.
 15. The bonescrew of claim 10, wherein the finger elements are configured to securethe bone screw to a bone plate.
 16. The bone screw of claim 10, whereinthe finger elements further include serrations.
 17. A locking bone screwlock comprising (i) a screw head; (ii) a proximal bone screw hole/plate;and (iii) a locking insert, wherein the screw head is spherical indiameter and is split with a plurality of finger elements, which arecapable of deflecting in and out, the bone screw hole is spherical,which matches the screw head such that the screw can be placed into abone plate at an angle and or provide screw angulation; and the lockinginsert comprises a shaft that comprises a plurality of arms that matewith the finger elements that divide the screw head.
 18. The bone screwlock of claim 17, wherein the screw head is able to flex inward enoughto allow the screw to pass through an interference point in the bonescrew hole.
 19. The bone screw lock of claim 17, wherein the screw headcomprises a hex incorporated for driving the screw and wherein proximalthe hex is a groove which creates a cavity that the locking insertcommunicates, which retains the locking insert in the screw head. 20.The bone screw lock of claim 17, wherein the locking insert is aseparate component that is assembled into the screw head to provide thescrew lock.
 21. The bone screw lock of claim 17, wherein the corediameter of the locking insert comprises a stop to the screw head andprevents any deflection.